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Date: Fri, 17 Jun 2022 18:05:12 +0800
From: menglong8.dong@...il.com
To: edumazet@...gle.com
Cc: rostedt@...dmis.org, mingo@...hat.com, davem@...emloft.net,
yoshfuji@...ux-ipv6.org, dsahern@...nel.org, kuba@...nel.org,
pabeni@...hat.com, imagedong@...cent.com, kafai@...com,
talalahmad@...gle.com, keescook@...omium.org,
dongli.zhang@...cle.com, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, Jiang Biao <benbjiang@...cent.com>,
Hao Peng <flyingpeng@...cent.com>
Subject: [PATCH net-next v4 6/8] net: tcp: add skb drop reasons to tcp tw code path
From: Menglong Dong <imagedong@...cent.com>
In order to get the reasons of skb drops, add a function argument of
type 'enum skb_drop_reason *reason' to tcp_timewait_state_process().
In the origin code, all packets to time-wait socket are treated as
dropping with kfree_skb(), which can make users confused. Therefore,
we use consume_skb() for the skbs that are 'good'. We can check the
value of 'reason' to decide use kfree_skb() or consume_skb().
The new reason 'TIMEWAIT' is added for the case that the skb is dropped
as the socket in time-wait state.
Reviewed-by: Jiang Biao <benbjiang@...cent.com>
Reviewed-by: Hao Peng <flyingpeng@...cent.com>
Signed-off-by: Menglong Dong <imagedong@...cent.com>
Reported-by: Eric Dumazet <edumazet@...gle.com>
---
v2:
- skb is not freed on TCP_TW_ACK and 'ret' is not initizalized, fix
it (Eric Dumazet)
---
include/net/dropreason.h | 6 ++++++
include/net/tcp.h | 7 ++++---
net/ipv4/tcp_ipv4.c | 8 ++++++--
net/ipv4/tcp_minisocks.c | 23 +++++++++++++++++++----
net/ipv6/tcp_ipv6.c | 7 +++++--
5 files changed, 40 insertions(+), 11 deletions(-)
diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index 74512e60ab12..90cdb7321926 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -246,6 +246,12 @@ enum skb_drop_reason {
* socket is full, corresponding to LINUX_MIB_TCPREQQFULLDROP
*/
SKB_DROP_REASON_TCP_REQQFULLDROP,
+ /**
+ * @SKB_DROP_REASON_TIMEWAIT: socket is in time-wait state and all
+ * packet that received will be treated as 'drop', except a good
+ * 'SYN' packet
+ */
+ SKB_DROP_REASON_TIMEWAIT,
/**
* @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be
* used as a real 'reason'
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 16da150150c3..1a88fabf0cce 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -379,9 +379,10 @@ enum tcp_tw_status {
};
-enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
- struct sk_buff *skb,
- const struct tcphdr *th);
+enum tcp_tw_status
+tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
+ const struct tcphdr *th,
+ enum skb_drop_reason *reason);
struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
struct request_sock *req, bool fastopen,
bool *lost_race);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index e1064273062a..f2ed9763d504 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1975,6 +1975,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
reqsk_put(req);
goto discard_it;
}
+ drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
if (tcp_checksum_complete(skb)) {
reqsk_put(req);
goto csum_error;
@@ -2049,6 +2050,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (drop_reason)
goto discard_and_relse;
+ drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
nf_reset_ct(skb);
if (tcp_filter(sk, skb)) {
@@ -2104,7 +2106,6 @@ int tcp_v4_rcv(struct sk_buff *skb)
}
discard_it:
- SKB_DR_OR(drop_reason, NOT_SPECIFIED);
/* Discard frame. */
kfree_skb_reason(skb, drop_reason);
return 0;
@@ -2128,7 +2129,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
inet_twsk_put(inet_twsk(sk));
goto csum_error;
}
- switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
+ switch (tcp_timewait_state_process(inet_twsk(sk), skb, th,
+ &drop_reason)) {
case TCP_TW_SYN: {
struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
&tcp_hashinfo, skb,
@@ -2144,6 +2146,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
refcounted = false;
goto process;
}
+ /* TCP_FLAGS or NO_SOCKET? */
+ SKB_DR_SET(drop_reason, TCP_FLAGS);
}
/* to ACK */
fallthrough;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6854bb1fb32b..dd640574d00f 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -83,13 +83,15 @@ tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw,
*/
enum tcp_tw_status
tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
- const struct tcphdr *th)
+ const struct tcphdr *th,
+ enum skb_drop_reason *reason)
{
struct tcp_options_received tmp_opt;
struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
bool paws_reject = false;
tmp_opt.saw_tstamp = 0;
+ *reason = SKB_DROP_REASON_NOT_SPECIFIED;
if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
tcp_parse_options(twsk_net(tw), skb, &tmp_opt, 0, NULL);
@@ -113,11 +115,16 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
return tcp_timewait_check_oow_rate_limit(
tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2);
- if (th->rst)
+ if (th->rst) {
+ SKB_DR_SET(*reason, TCP_RESET);
goto kill;
+ }
- if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt))
+ if (th->syn && !before(TCP_SKB_CB(skb)->seq,
+ tcptw->tw_rcv_nxt)) {
+ SKB_DR_SET(*reason, TCP_FLAGS);
return TCP_TW_RST;
+ }
/* Dup ACK? */
if (!th->ack ||
@@ -143,6 +150,9 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
}
inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN);
+
+ /* skb should be free normally on this case. */
+ *reason = SKB_NOT_DROPPED_YET;
return TCP_TW_ACK;
}
@@ -174,6 +184,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
* protocol bug yet.
*/
if (twsk_net(tw)->ipv4.sysctl_tcp_rfc1337 == 0) {
+ SKB_DR_SET(*reason, TCP_RESET);
kill:
inet_twsk_deschedule_put(tw);
return TCP_TW_SUCCESS;
@@ -219,8 +230,10 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
return TCP_TW_SYN;
}
- if (paws_reject)
+ if (paws_reject) {
+ SKB_DR_SET(*reason, TCP_RFC7323_PAWS);
__NET_INC_STATS(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED);
+ }
if (!th->rst) {
/* In this case we must reset the TIMEWAIT timer.
@@ -232,9 +245,11 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
if (paws_reject || th->ack)
inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN);
+ SKB_DR_OR(*reason, TIMEWAIT);
return tcp_timewait_check_oow_rate_limit(
tw, skb, LINUX_MIB_TCPACKSKIPPEDTIMEWAIT);
}
+ SKB_DR_SET(*reason, TCP_RESET);
inet_twsk_put(tw);
return TCP_TW_SUCCESS;
}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index dbe356a166c5..9aeb0a7b7c12 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1644,6 +1644,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
reqsk_put(req);
goto discard_it;
}
+ drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
if (tcp_checksum_complete(skb)) {
reqsk_put(req);
goto csum_error;
@@ -1715,6 +1716,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
if (drop_reason)
goto discard_and_relse;
+ drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
if (tcp_filter(sk, skb)) {
drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
goto discard_and_relse;
@@ -1766,7 +1768,6 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
}
discard_it:
- SKB_DR_OR(drop_reason, NOT_SPECIFIED);
kfree_skb_reason(skb, drop_reason);
return 0;
@@ -1790,7 +1791,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
goto csum_error;
}
- switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
+ switch (tcp_timewait_state_process(inet_twsk(sk), skb, th,
+ &drop_reason)) {
case TCP_TW_SYN:
{
struct sock *sk2;
@@ -1810,6 +1812,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
refcounted = false;
goto process;
}
+ SKB_DR_SET(drop_reason, TCP_FLAGS);
}
/* to ACK */
fallthrough;
--
2.36.1
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